Nerve Tissue: Neurons + Glial Cells

Question 1

Nerve Tissue

Answer 1

is composed of cells (neurons) that are specialized at conveying information and their support cells (glial)

Question 2

What is the Neuron doctrine (1891)?

Answer 2

individual neurons serve as the signaling elements of the nervous system

Question 3

How many neurons are in the human body?

Answer 3

> 100 billion neurons that vary in size and shape

Question 4

How do neurons receive, process, and transport signals?

Answer 4

Neurons utilize electrical and chemical mechanisms

Question 5

What are electrical signals used for?

Answer 5

To convey information rapidly from one neuron to another

Question 6

What are chemical signals used for?

Answer 6

To carry information between part of one neuron and part of a second neuron or effector cell (via synapse)

Question 7

Why are neurons structured into regions?

Answer 7

So that organelles are distributed in a pattern that supports neuronal function

Question 8

Neurons-Regions: Cell body (a.k.a Perikaryon)

Answer 8

Contains the nucleus and surrounding cytoplasm, but does NOT include cell processes

Question 9

Neuron-Regions: Cell Body Structure

Nucleus

Answer 9

-Euchromatic (pale-staining; active in RNA synthesis) with a prominent nucleolus–> 92% of the human genome is euchromatic.

Question 10

Neuron-Regions: Cell Body Structure

Cytoplasm

Answer 10

• Abundant rough endoplasmic recticulum (a.k.a RER & Nissl substance) and polysomes
• Well developed cytoskeleton

Question 11

Neuron-Cell Body Functions

Answer 11

(1) Trophic (related to nutrition/metabolism) center of the cell
(2) Receptive to stimuli

Question 12

Neuron-Regions: Dendrites

Answer 12

Elongated processes emanating from the cell body; most neurons have multiple dendrites

Question 13

Neuron-Regions: Dendrites Structure

Answer 13

Short, tapered, and highly branched

Question 14

Neuron-Regions: Cell Body Structure

Answer 14

Large and spherical in shape

Question 15

Neuron-Regions: Dendrites Structure

Cytoplasm

Answer 15

Organelles are similar to cell body except their are NO Golgi complexes

Question 16

Neuron-Regions: Dendrites Structure

Dendritic Spines

Answer 16

Specializations at some synapses

Question 17

Neuron-Regions: Dendrites Functon

Answer 17

(1) Receptive to stimuli, transmit signals towards cell body

Question 18

Neuron-Regions: Axons

Answer 18

Elongated processes emanating from the cell body

**Most neurons only have one axon

Question 19

Neuron-Regions: Axons Structure

Answer 19

Long, cylindrical and not highly branched

Question 20

Neuron-Regions: Axons Structure

Cytoplasm

Answer 20

Organelles similar to the cell body except NO RER or polysomes

Question 21

Neuron-Regions: Axons Structure

Axon Hillock

Answer 21

Pyramid shaped region where the axon emanates from the cell body, devoid of Nissil substance (area w/o purple staining)

Question 22

Neuron-Regions: Axons Structure

Terminal Aborization

Answer 22

Branched distal portion of axon

Question 23

Neuron-Regions: Axon Function

Answer 23

(1) Generate and conduct signals

(2) Receptive to stimuli

Question 24

Neuron-Regions: Presynaptic Terminal (a.k.a Terminal Bouton or Terminal Bud)

Answer 24

• Dilated termination of an axon on another cell at a chemical synapse
• NO myelin sheath

Question 25

Neuron-Regions: Presynaptic Terminal Structure | Cytoplasm

Answer 25

Organelles similar to cell body, except more mitochondria and the presence of small, spherical, membrane-bound synaptic vesicles containing NT

Question 26

Neuron-Regions: Presynaptic Terminal Structure | Active Zones

Answer 26

Regions along the presynaptic membrane concentrated with voltage-gated calcium (Ca2+) channels and synaptic vesicles

Question 27

Neuron-Molecular Transport Systems

Answer 27

Composed of the well-developed cytoskeleton | Function: to transport substances b/w the cell body and the processes at slow, intermediate, and fast speeds

Question 28

Neuron-Molecular Transport Systems: Types

Answer 28

Anterograde: carries materials from the cell body to the periphery Retrograde: carries materials from the periphery to the cell body--> ex. can lead to transmission of viruses!!

Question 29

Neuron-Categories | Motor

Answer 29

General Somatic Efferent General Visceral Efferent Special Visceral Efferent

Question 30

Neuron-Categories | Sensory

Answer 30

General Somatic Afferent General Visceral Afferent Special Somatic Afferent Special Visceral Afferent

Question 31

Neuron-Categories | Interneuron

Answer 31

Local-all processes are confined to a small area | Projection-long axons connecting different areas

Question 32

Neuronal Processes: Types

Answer 32

``` Multipolar = more than one dendrite and one axon Bipolar = one dendrite and one axon Pseudounipolar = a single process that is close to the cell body and gives off two branches (central + peripheral axons) ```

Question 33

Glial Cells: Structure

Answer 33

10x more abudndant than neurons | vary in size and shape

Question 34

Glial Cells: Function

Answer 34

-surround and support neurons, but do NOT participate directly in synapse interactions and electrical signaling

Question 35

Glial Cells: Type-Function/Location | Macroglia

Answer 35

Astrocytes (CNS): structural support, repair processes and form blood brain barrier Oligodendryocytes (CNS)-produce myelin Schwann (PNS)produce myelin and ensheath axons **Oligodendryocytes and Schwann cells that do not produce myelin or ensheath axons-->called satellite cells & are associated with neuronal cell bodies

Question 36

Glial Cells: Type-Function/Location | Microglia

Answer 36

-Macrophagic activity (CNS)

Question 37

Glial Cells: Type-Function/Location | Ependymal

Answer 37

-Line cavities (ventricles) (CNS)

Question 38

Myelin Sheath: Structure

Answer 38

- Segmented, multimellar, lipid rich, wrapping of axon | - Formed by the plasma membranes of Oligodendrocytes and Schwann cells

Question 39

Myelin Sheath Structure: Internode vs Node of Ranvier

Answer 39

- Internode = segment of axon covered w/myelin) | - Node of Ranvier = interval at which axon is NOT covered by myelin; b/w internodes

Question 40

Myelin Sheath: Function

Answer 40

- Provides electrical insulation | - Increases speed of impulse conduction by saltation